Energy from food is primarily provided by carbohydrates and lipids. Carbohydrates usually supply the immediate energy needs and their excess is stored as glycogen in the liver or converted to lipids. Lipids can also be metabolized as immediate energy providing substances but their rate of energy provision is relatively slow and they are generally stored in the body for use in states of deprivation. Lipid is stored in the body mostly as fat under the skin and consumption of lipids and carbohydrates beyond the metabolic need leads to fattening. The associated medical and aesthetic problems, are a major concern in modem society.
Apart from surgery and dietary means for reduction of fat absorption in the small intestine, there are presently no satisfactory, means for reducing fat storage in the body and the current means of choice are still diet and exercise. There is, however, a desire for drugs which will reduce fat accumulation by inhibiting lipid and lipoprotein synthesis in the liver. Recently, a series of .beta.,.beta.' tetramethyl substituted .alpha.,.omega. dicarboxylic acids (MEDICA) have been synthesized and suggested as potential anti-fattening drugs.sup.(1-4,6-9). The most potent drug of this series was found to be the hexadecane derivative (MEDICA 16). It was demonstrated that MEDICA, which is a non-naturally occurring fatty acid, could inhibit biosynthetic pathways of triglycerides and cholesterol in the liver. Experiments with MEDICA 16 given in the diet to normal and obese rats have indicated a strong inhibition of glyceride and cholesterol biosynthesis in the liver evidenced by a marked reduction in their serum contents.sup.(3). Furthermore, in the obese animals adipose tissue was reduced by about 75% over the whole body concomitantly to extensive weight loss.sup.(5). However, the metabolic clearance of these compounds via integration into glycerol esters or via oxidation is relatively slow due to the presence of carboxylate at the two edges of the molecules and the .beta. alkyl substitution. Despite their impressive effect, MEDICA are expected to exert a long term toxicity due to their non-compatible molecular structure. Thus, chronic intake of MEDICA, which is required for maintaining a low fat state, would likely be associated with adverse toxic effects in the long run.